Logan model 200 shifter rack and back gear engagement/adjustment

medida

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Hope folks can help me here

Got an old logan model 200 that I have taken apart, cleaned/regreased the bearings, painted the unit, etc. Some teeth were missing on one of the reverse gears and on the mitre gear in the apron (have found replacement parts for these)

Without the back gear engaged, the unit runs very well (did not do that prior to the refurbishment)

However, I am having problems with the back gear alignment to the shifter rack

I have followed these instructions
http://lathe.com/ll-group-archive/logan_lathe_back_gears.html

the issue that I have is when I roll the eccentric around to engage the back gear....I roll it as far as I can (it then becomes an interference at the gears and no backlash). When I put in the shifter rack, as it advances into the headstock it starts to move the eccentric, so backlash starts increasing. By the time I get to the latch position, the back gear is mostly not engaged.

The only way I can see around this is if the eccentric shaft can never achieve an interference between the two gears. It's like I need to rotate the eccentric shaft/gear another 20 degrees or so....but am not able to ....because I achieve a zero backlash and interference

I have had the unit all apart and the spindle out....but do not see any errors in how I have put it back together (and it does run very well with no backgear engaged)

any thoughts?
 
I think you need to read the page you referenced again. :whistle:

When you push the shifter rack IN it disengages the back gear. The spring loaded lever should position the gears correctly when the rack is pulled out. You may need to adjust the collar on the end of the shaft a little.

Hope that helps.

Steve
 
Yes, I know when the shifter rack is pushed in the back gears are not engaged

The issue that I have is I need to rotate the eccentric gear another couple of teeth more but am not able to do this, as the back gears are now at an interference interface (that is, I have completely removed the shifter rack out of the headstock)

With the shifter rack out, I have rotated the eccentric gear as far as I can. When I insert the shifter rack, as soon as the shifter rack teeth start to engage, it starts to disengage the back gears. By the time I am at the latch position, the back gears are almost disengaged. When the shifter rack is fully inserted, the back gears are disengaged.

I cannot rotated the position of the eccentric gear relative to the shifter rack any more, so that the backlash is correct when the shifter latch is in place
 
I guess what you're saying is that the teeth in the rack are engaging the teeth in the gear too soon? I think that would be the only thing that would cause what you're describing. If that's the case I'm not sure what to tell you. The distance between the teeth and the latch on the shifter rack is a fixed, calculated dimension per the design from the factory. Maybe someone reworked the shifter rack?????

Sorry I can't be of more help.

Steve
 
Been a long time since I have messed with this, but, I think you are saying with the rack plunger pulled out ... the gears are not engaging.

I think you need to try and shift the engagement back to the second (or even third) tooth on the rack. Push the rack in a little before lifting the eccentric shaft completely. This is what Scott is talking about in point 6 of the link you posted. You will only push in the rack a tooth width at a time.

Like I said its been a long time ... but I think this will work.
 
Let me try and say this differently

The shifter rack is out of the headstock. I rotated the shifter gear until the two back gears (28 Tooth and 70 Tooth) are completely engaged with zero backlash. I cannot rotate the shifter gear any more

I then start to insert the shifter rack. As soon as the first shifter rack tooth engages the shifter gear teeth, it starts to rotate the eccentric and it backlash starts to increase. THe shifter rack has not yet protruded out from the back side, so I do not have any shaft exposed to lock a collar on. By the time the shifter tab hits the headstock, the back gears are almost totally disengaged

So I do not understand how I can change the position of the shifter gear to the shifter rack to get the necessary backlash. The only way I can see to do this is to take the eccentric out and install the shifter gear....then put the eccentric back in. This just does not seem right that this is how it works. I would expect that you should be able to adjust the backlash without having to take stuff apart
 
It can be a pain to adjust. :angry: I just did this on my 1922 following Scott Logans instructions.
I ended up cutting a 1/4" dowel about 6 or 8 inches long and using it as a gentle pry bar wedging the bk gear in place after I rolled the the shaft to a point in its arc upward.
then push the selector rod back in to roll the gear into place. I know I'm clear as mud but it works just like the Logan instructions say, just keep trying at different positions of the bk gear arc and it will work. I completely agree it can be very vexing but my lathe sure is quiet now in back gear. I do love my Logan.:))

Kevin
 
You may also want to consider slotting one end of the eccentric shaft, per "Redlinemans Logan 200 Rescue".
That might make the adjustments go a little easier.
 
I'm tickled to see this thread, I've been wanting to ask about this but really haven't had time to mess with it yet. I have a 1920-1, my back gears only engage when I push the shifter all the way in, but nothing if its out a little. I'll go back & read the link yall listed & try to figure it out.

Dwayne
 
Ummm...

People do realize that the back gears are engaged by pulling and locking the shifter rack OUT, eh? You didn't know that... really?
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Don't worry. I had to clue into that myself. My lathe didn't even HAVE a shifter when I started on it, so I had to figure that one out for myself... in time.
 
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